It’s come to this, on his 146th day in office: The president, under investigation for obstruction of justice, attacked his own deputy attorney general for orchestrating a “witch hunt” against him.

Sometimes my role as a columnist is to advise readers not to overreact, to maintain perspective. Today my advice is to buckle up. Brace yourselves.

I’m not sure for what, exactly. President Trump firing Rod Rosenstein or taking moves that would force the deputy attorney general, and perhaps others, to quit? Firing special counsel Robert Mueller, whose probe has pushed Trump to this frenzied state? Using his pardon power in an effort to shut down the investigation, on the theory that Mueller would then have nothing left to probe? Pardoning himself, a move of contested legality that even Richard Nixon balked at? Facing impeachment proceedings, however unlikely that may be with a Republican-controlled Congress?

That any of these seem within the realm of possibility is the measure of how unsettled, and unsettling, this moment is. Actually, that’s an understatement. This situation is alarming in a way I have never experienced in almost four decades here.

I am not alone. “The message the president is sending through his tweets is that he believes the rule of law doesn’t apply to him and that anyone who thinks otherwise will be fired,” Sen. Dianne Feinstein, D-Calif., said in a statement Friday. “That’s undemocratic on its face and a blatant violation of the president’s oath of office.”

Trump had a moment last week when he rose to the occasion, however fleetingly. After the shooting at the Republican congressional baseball practice, the president struck the right note of calming unity: “We do well, in times like these, to remember that everyone who serves in our nation’s capital is here because, above all, they love our country.”

Love was not so much on the president’s mind the rest of the week. He went after “obstructionist” Democrats; “cowardly” James Comey, the fired FBI director; and the “Fake News Media … so wrong and so dirty.”

But mostly, as reports about his legal peril multiplied, Trump became increasingly worked up about the Mueller probe. He perceives himself as the ultimate victim — first of a double standard under which he is blamed while Clinton and her allies, such as former Attorney General Loretta Lynch, escape responsibility. “Crooked H destroyed phones w/ hammer, ‘bleached’ emails, & had husband meet w/AG days before she was cleared- & they talk about obstruction?” Trump tweeted.

Yes, Mr. President, because you are the president; she isn’t. Because as dumb and self-destructive as some of the Clintons’ conduct was, there was no evidence of obstruction and, as Comey said, “no reasonable prosecutor” would bring a case against her.

The second, perhaps even more deeply felt, aspect of Trump’s victimhood involves his conviction that any investigation of him constitutes an unfair attack by political enemies. “They made up a phony collusion with the Russians story, found zero proof, so now they go for obstruction of justice on the phony story,” he tweeted. “You are witnessing the single greatest WITCH HUNT in American political history — led by some very bad and conflicted people!”

Where to start with the distorted thinking exhibited in these tweets? On collusion, Trump is, at best, premature; there is not “zero proof” but a continuing investigation into campaign and transition contacts between Trump associates and Russian operatives — contacts that Trump aides have consistently minimized if not lied about directly.

As to obstruction, Trump’s wounds are entirely self-inflicted. He has seemed determined — frantic, really — to see that the case against fired national security adviser Michael Flynn is dropped. If you credit Comey’s sworn account over Trump’s news conference denials, Trump demanded Comey’s loyalty; pressed him to drop the case against Flynn; and eventually fired Comey himself because of his handling of “this Russia thing.” As Comey might say, no reasonable prosecutor would fail to investigate in these circumstances.

What Trump derides as a “phony witch hunt” is the legal system working as it should. Attorney General Jeff Sessions needed to recuse himself. Rosenstein needed to name a special counsel. And Mueller needs to pursue the investigation, impartially and fearlessly, to its logical end.

That Trump now feels the need to attack seasoned prosecutors for simply doing their jobs speaks volumes — and says nothing reassuring about the lengths to which Trump, for whom self-preservation has always been the top priority, might eventually go.